A corpoe



Oct. 9, 1928.

BEST AVAILABLE COP 1,686,684 L. l. DAvls CONTROL SYSTEM FOR ELEVATORS Filed Oct. 29, 1925 2 Sheets-Sheet l BEST AVALABLE COF" 6, La 8 .n

w /5 m5 mmm m2 0/0 9 BB1 M Vn9. l wm Lmw mm L5M mt m F c Oct. 9, 1928.

ARMATURE VoLTAGe ARMATuRE VOLTAGE @5% 1416 @Hom/w13 Patented Get. 9, 1928.

BESTAYAILABLE coP essere@ 12b-vie..

nmiwlro'mr, inriessreionjro overs signifierait' commmngor @Rdnr i 'CITY,'NEWJERsiiY A confesiafiie's or NEW JERSEY.. v

CONTROL SYSTEM refe ELEVATORS.

Appiiceon medocwbr 29. i325. serial No. 65,612.

The invention relates: to control. systems, and particularly to -controlsystems for elevators.

In elevato control systems wherezthe ele- -vator motor is-supplied withicurrent--by a: Variable.voltz'nge'generator, the generator' is required' to operate' over a wide range of E.' M..F.-values varying'- from a maximum' in one direction toa maximum in the' other; fWhere l"'- sclfsleveling apparatus is`-employed,th'e generat'or'is-requiredA to operate at lowvaluesof F.- in bringing the car to a level with a desired: landing. Due'l to thefresidualflux of I the-generator ield, tl'ie 'E' values obl l" tained foia; 'giveniv'alue 'fili'eld current dur-` ing l'the `leveling'operationfvary'- considerably, f dependingoxithe p revioiis niagneticA-stateof the machine and w :ether the caris approach# ingI tlie 'landing'. or returning f to- 'tlie" landing 1 aier an: overrun 'f `Such 'variations'l in'- EQM-f Fnyaldv's .cause undesirablefivaiviations in the operation 5 of the car duri-ng j the leveling-A pi0d."' if? .lrrsfiff :v

"'O x1'e==fea'ture of the invention istlovcause nioreffunfornopertionf*of thfe elevatorcr" during theleveli-ng-p'eriod by minimizing'the eiect'sof the-residual x' ofthegenraton" l--"f .''iAnothei" 'featui'eresides controlling tl'ej strenrthoithe.generator'ielddie to its's'eries t 301 fliwvindng-zuringfthe ,'Ievlniflperiod in@` sudhfn'anner "aszto bring: f the elevator i car" qiickly' positively" toftl'l'e' 'jlandingregard-f less ofwlietli'r-itlhas' underrun orpverrnthe" -1 nizw.

apparent from the following-fdsriptin* taken in 'fc-onnection With the Vafcfcorn'p'anying drawings wherein --one' embodiment' of'fthe A I if with discharge 'resistances 28, SO'ndSfPfor 4:. i "i Figure Iris' adiagrni'of anelvator controlli:

v dilerent'hditions ofoperation; 32 and 33l system; 1 Y- a portion ofthe elevator' system?illustrating" the xnan'ner which -the geneijatorffield 'v v'indl 4' ings arecontrolled-durmgth'elevelmgjo'perai i 35 respectively.' '361s the armature'arid'afisl4 tion; and Y Figures 3?, tand 5 are hysteresis curves eine. played to illustrate the'mvention.

Noattempt is made in Figure'l'to sliowthe?" coils and contacts of the'A various electroniagil neticswitolies intheir assoclated positions, -a' straight` diagram being er'iiployeclwhereinI lhecoils'and contacts of the variousswitches, :isep'arated In such manner as to render the circuits'mvolved relatively s1mple.` Also'the f the supply mains. -In order tofsuitthe type' pars of-other 4switches and-al'iparatus are separated in the interest ofisimpliying-the diagram. For a clearer understanding ofthe invention, the stationary? contacts ofthe switches are illustrated in cross sectom It is te understood that the system'illustratd is chosen nierclv for convenience of description and that, although descritied iniconju'nction with a ear switch controlled system-,- the invention equally applicable to v'otherftyp'es 65 of elevator systems 'such asi push button coiltrol systemsancl to othersystems:employinga-work motor spp1ied-ivith currentifro'mfthe generatorof a 'motor generator setff'uff fifi Thevinotorfgeneratorset comprises aa. .df'rivl 7 'f ing niotor= illustrated-:for oonvenieno'efoff description as of the fdiiectxcui'renttypeQ'adj a variable voltage direct current generator 12;. The armature' ofthe drivingamo't'or isfdesigf4 mated 13 and its field winding-'l-ts-'ljhe 'arx'n' 75 ture of the enratbrl is -d'esiginatd "15, its series eldwinding 16, its separately ex'sitcd fieldt winding being-divided into stwo' portions 17 and 18.'.'1fT'l're elevator motor is' designated as wholeby' -the numeral 120,' itslarmaire s@ beingl designated-21 nd-'tseld 22:+I finl adjustable resistance :29 iinj' sh'unt; z toiftlie' generator "series: Dischartge'resi'sttnces 23- and 24:: areprvded-i i-"mf-ihe portions 17 and 18-rspectively3 the 85 f" generator .separatelyiexcited i field Disehargeresistlance .'25 is p`ro vi' `led''-forz Ethelr elevator 'io'tor eldivinding: 'ijAlresiStlfic' 262is`providedlfor controlling thestrengtlr of? theAl generator field and therefore'l the "voltajg'f 90-- i' applied'ito'jthey elevator 'motori' armature. 3 27 the 'field winding of the `motor38 for l'novin'gj if 'the rollersof the leveling switch into position to clear the leveling cams.. 40 14.1'arl'th'eE direct current supply mainsf'42 1s afdouh'le; 105` pole knife switch for connecting the system'to'A otfdiagram" employed; ther-blades Vofthisu` switch are shown separated. f'jThe car switch is designated as a'wlolehy theiiunieral'43;111-0-5 44 is thesafety switch in the car.. The various safety, limit,istop and emergency switches and door and gate contacts are omitted in order to simplify the description.

designated as follows:

A-potential switch, B-up direction switch, C-down direction switch, D-up slow speed leveling relay, lil-down. slow-speed leveling relay,

,F-'accelerating'switch Gmaintaining. relay,

H-brake switch,

J-l-protective relay,

K-auxiliary protective relay, L-slow down switch,

.. M-series field relay,

--Nffseries field switch,

. .Pf-leveling switch motor relay, 1 Throughout the Ydescription 'which follows, thesezletterse in, ad'dition: to'the usual reference numerals, -willrbe applied to the parts othe abovef,enumeratedaswitches.l For eX- ample',r-c'ontacts B66 arefcontacts on the up direction'iswitchywhile:actuating coil A 45 is the coil that operates the potential switch.

The-electromagnetic Sswitches arev shown in fitr. their;deenerglzedppositions. i; v

Upon the.' lclosing .of vthe` Imi-fe thedrivingfmotor 1l,fielevator motor field winding 22.' andi p'otel'itial-v switch actuating coil ;A45, are energized, :the circuitI for coilf describedmightbe termed normal-f f Assume .that the.- systennis `:design-ed for-Y an installation fof several. {ioors :and that the car isatarestat the first oorlanding. vIn

orderl to ,'start; thecar, inthe l up direction, the-A operator, moves the car switch' into positionswhere its'contactbar 52 bridges con- ;tacts 53, 54,; y and-56. vUpon' the contact bar 521 engagingcontact 5 4., a circuit-is completed for thefactuating coil B57 of theupj direction. switch,andythe'hactuating coilvr H 58 of the brake, switch..j Thiscircuitlnay be traced ffrom,the lefthand blade of switch 42, bv

waycofline'i79 through `contacts'A 50,' by

way of linelthrough coils H 58 and B 57,

contacts`r 54-vandj53 of the carswitch, by way of line lthroughl contacts C 62, line 63,

switch 44, line v46,byiwayoi` line 89, to thev switch 42,

y fe,=da;iyi`;ng-. motor. startsgfin operation, f 1 tngingthg: generator; 12fup'etofull.speed.` .f Starting ineans, .for ytliendri'ving motor? are'- omitted? to Simplify (the description. The po.-

1,666,664 BESTAVAILABLE COP- right-hand blade of switch142.: The engagement of the contact bar and contact 55 prepares a circuit for the actuating coil F 83 of the acceleratingxswitch. The engagement of the contactbar'and contact 56 completes a circuit for the actuating vcoil P 59 oi' the leveling switch anotor relay. This circuit may be traced from the left-hand blade of switch 42, by way oi' line 79 through contact A 50, by way of line 92 through coil P 59, contacts 56 and 53 of the car-switch, to the right-hand bladeV of switch 42 as above traced.

It is preferred to provide the direction switches with a vmechanical'interlock to prevent their simultaneous operation'. Such'an interlock may be of the form of a walking beam pivotally mounted for engaging catches on the armatures ofthedirection switches. Upon operation of the up direction switch'in response to the energization? of-its actuating`- coil B 57, contacts B separate and con? tacts vB 66, B 67 and B-681engagel` The sepa-- ration of contacts .B 65 breaks the circuit leading from theca'r switch down feed contact 70, 'contacts B, 65 and the corresponding down direction switchy contacts C 62 servingas electrical interlocks. rl`he engagement of contacts B 68fprepares the circuit-for the upV direction switch holding coil Bf 71 and the brake switch'holdingfcoil H 72.A The'. e111 gagement of'contacts B66 and B 67 completes a circuit for the generator separately es xcitedli'ield winding; This circuit 'may' be traced from the left-handrblade of switch 42, bygway; of; -line'7 9 .througlr'k contacts `A 50 and' resistance 26,:byl way of line 7 3 through contacts B 66,; by way ,offline 74 through field winding portionl7, actuating coilG oi' the :maintaining relay, slow-down switch. contacts -L `7 6, field winding portion- 168, vby way of line'89. through contacts B67' 'andA contacts A. 51, to the right-hand :blade off switch 42 Relay G does not operate -at'thisf time as insuicient current is. supplied to-its actuating coil..,. p

The brale switch H operates simultaneous z lywith the .direction switch' B.`1' Switch H, upon operationfcauses-the separationl oi contats H 77 andH78 and the engagement'of contacts H 80 and H 81. The separation of 1 contactsy Hj 77 disconnects the generator separately. excited field winding from the' genf4 erator armature.- lThe purpose of contacts H 77-will be seen l'romla'ter description. The separation of contacts H 78 disconnects resistance 3l fromvv across the brake release coil 27. Resistance 31 being of low ohmic value, f its disconnection before contacts H 80 engage prevents excess power consumption from mains 40 and 4l.A The engagement ofcon.- tacts H 8O completes the circuit for the brake releasecoil 27. This circuit Vmay be tracedv :Eromthe lefthand blade of switch 42, by way of line 79 throughA contacts A50, byfway of los l III 1,ee6,e84 BEST AVAILABLE COF 3= through contacts yH 81,- reactance S5'and coilv F 83,-.contacts and 53 ofthe car switch, by wayiof line lthrough 'contactsG `62, line 63.

switch 44, line;46, line 8 9, to the right-hand eration, causes the-.;enga.'gement' of contacts P. 93, completing the-:circuit for ,the leveling' switch n'iot'or'.:- Thisci'rcuit may be traced fromv the lefthandbladefof switch 42, by Way of line 79 through contacts A 50,'by1way of 1ii1e` 94.1' tliroughl armatiueffand field Windingf; of motorS'andcontacts P93; by Way v of line 89 through contacts A51, to the righthandfbladeofsvv-itcli .1.1.21 The, leveling switch. m'tor; act'stomove-z the :levelinfq switch opere" :ating follers so'asto'c'learfthe leyeling cams' diigxovemnt'ofthe ca'iuxf f This operation" will-be eitplained'latr'. .Y :.'Thebrake releaser coil 27 being; energized tactsA 515,' to theright-hand blade of switch short-circuits 'resistance'y i 26', increasing' the voltage. applied 'to :generator-field Winding portionsfl'.l and 182 .'Thusthe -`generator volt# .age-is broughtup.- to its-full value and the motor cornesp-:to'fiill speedf Also' sreflicient current 4is--nowA supplied to'thecoil G T5 to cause-the operationof'tlieinaintaining relay. Thus" contacts G I97' engage," bypassing ac- -celeratingswitch?contacts'FzSS. ult is to bc ld medina understood tliat'several accelerating switches may be employed to short-circuit successively sections of resistance 26; all but one, illustrated as Short-circuiting. the Whole of the. resistance, being omitted in order to simplifyY 7 the description. v

rElie starting of the car in the down direction is accomplished in a similar manner and will be only briefly described. The operator moves the car switch into position Where its. contact bar 52 bridges contacts 70, 98, 1GO- and 101.- Upon the engagementofthe. con-i tact bait' and contactSS, a circuit is completed for the down direction switch actuating coil.' C 102 and coil H 58 wliich'circuit may. be traced from the left-hand 'blade of switch 42, through coil H 58, as previously traced,- by way of line 103 through coil C102, carV switch contacts 9S and 70, by way of line': through contacts B (55, to the right-hand blade or switch 42- as previously traced.- e="l`he enfl gagen'xent of the contact baran'd contact' '.100 prepares a circuitzfoncoilel SSffand'theren-x gagenient of the 'contact'.'ba-rf an'dzontact '1012 completes a vcircuit for thecoiilfEbQfzbyfway of line lO-l. AThe donn direction-'svitcli,a1po1 operation, causes the .separatioir'ocontacts' C 62 vand thel cngageiiientocontacts TCE 1100,.' C 10S andC 107, these contactsiorresponelingg with up direction-switch .contact iB* 65, .BIGGQ 9 B 67 and B 68 respectively." "lrhelioldingicoi-l, of the down direction 'switchistdesigxiatedc 06e. The ciicuitjor coil F583 is'lcompleted' by contacts HSI-as beforex; Fzur'tlierTtba-nl this, the operation: of start-ingetheca in the .l down direction fis the samer-ias described '-onl startingfit in the'up'directionz is .ii ;;r Assume 'fthatthe can fisarunninfi" in the iup., direction.l 'and that: .the operator.; centerse t-hl car iswitclfrbetweeii' vtle secondgaiidffthrdnl floors in order. to stopt-an thethirrl'zflo'or land-Si ing. 'Uporr thef-disengagexnntrorthe com tact'. 'bari 52 r and. con-tact f .'56,Y thelcircuit fora the leveling switchmbtorrelayfactnatirlg coilji P broken. The relayoreinaihs inoperateel ed condition, however', duebofits holding; t P 91` #The disengagenientof:contact/5%ands accelerating switch actuating coilF'SnThe accelerating: switchgltlieret'ore, drp'sfolt, 1 causing the separation or". conta-'ots E 88aiid'a F 90 andi tlie vengagement.: edf: contacts Sii;

The separation 'of conta'cts.Fi=88ssi1nply=iiif= 42. The purpose of the energizatioir of these'f holdi-ngcoils will be seenY romlate-rdescrip I tion.` TheV engagement of contacts F 90 f preparation-'for the next staitingf. operationing maintained by'contacts G 957. I"lfhcop'- aration of contacts F 90 removes? t'li`e short-l circuit for resistance 26,' decreasing fthe! strength of the `generator `field winding por'- tions 17 and 18.-Tlius the generatorEfM. F.' l is decreased and the speedo the elvator-'nio-f toi-.fis reduced. Dischargeresistances 23 and 24 act toslnooth out-'tbe retardation. The cnf ,qagement of contacts F 87 short-circuits the 1 holding coil P 91 of the leveling switch i'notor1 relay. The disengagement of contact 54 and contact bar 52 breaks the circuit for actuating.

coils-B 57 and H 58. l The up direction switch.

and brake switch are maintained in operated condition, however, by their, holding coils,

B 71 and H 72 respectively. l The leveling switch motor relay l), dropping outnpon the short-circuitingot coil P 91, causes the separationof contacts l? 93 T to deenergize the leveling switch motor 38. In this manner the operating rollers of the leveling switch are extended for engagement by the leveling cams. Referring briely to Figure 2,the leveling switch motor is operatively connected to the leveling switch by means of an arm 108 oni the-motor shaft, a connecting link 110 and a lever' 111. In the starting operation, the motor 38 being energized, arm 108 rotates, acting through lint: 110v and lever 111 to move the leveling switch as a whole about a pivot. In this manner the leveling switch operating rollers 112 and 113 are movedl into position: where they do noty engagesthe leveling/Canis` 114 and 115' during wmotionofthe car, a? stop beinffprovided to determine the eXtento themovernent.' It is to'be understood that leveling cams are pron vided for each floor. The leveling switch i'spivoted on a braket 116. secured to the car 3; frame. :the` stoppingoperation; upon fthe.- deenergization of the levelingswitch motor,

a. spring4v (notshown) moves thel lever 111 and therefore .--the leveling switch' back;y into Ithe, first described position" withsthe rollers.v 112 i and 113,-.:exte'nded.: for. .engagement hy.; the.

leveling? Teams :Each pair '-oigleveling con- L tacts 32,' 33, 34 and .235'.1comprises ast'ationary contact and'- ai movable.rcontactzdperated. by

th Vfengagementsofggits; correspondingA roller im and leveling foams? The '.:Eastf-V spedf :contacts-.-

34 ardc35tare f arranged to. separate 'before vf their corresponding slow" speed: contacts :32` and 33zin? thev leveling operationir", Springs (not shown) nare' provided. for; causing the' separation. of :the contacts 'lof thev pairs 'as therlevelingfl operation isveected-fandfstops l arezprvided for determiningathe eiitent` 'ofy movementfofthe rollers as. theyfride Ofi the leveling cams. 5U

vertical surface of up leveling ca1n11'4l before relay G- drops out., :The engagement. of up slow speed leveling contacts {i2/completes a circuit for actuating coils H '58 and B 57 andVv up slow speed levelinggrelayactuating coil y Y, nected to the mains .40 and141 byftheengagef-? D 117. This circuit may be traced from the left-hand blade of switch 42, by way of line 79 through contacts A 50, by way of line-6() :through coil H 58, coil B 57, contacts 32 and coil D117, by way of line 89 through contacts A 51, to the right-hand blade of switch 42. The engagement of' fast speed leveling contacts 34 by-passes resistance 118, the purpose -0twhiclrwill be explained below; :The energization of coils H 58 and B57 has no particular effect at this time as the up'direction switch and brake switch are being maintained in operated condition by coils B 71 and H 72. Relay G, however, drops out as soon as the.: 2 l current lowingthrough :its actuating'coil drops to a predetermined value, thecurrent being sustained by the action offield winding portion 17 and discharge resistance 23. I AS a result, contacts G 97 separate, deenergizingholding coils B 71 and H72. The up direction switch and brake switch are then maintained operated by coils B 57 and H 58.' .A Had= the slow speed leveling contacts not been in engagement when t-herelay G dropped out; their subsequent engagement as roller `112- rode onto the vertical surfaceof the. cam' would cause'the energization ocoilsHix58- andB', As set fort-h above, actuatingcoilDfllZf of the up-slow speed leveling relay was'enr-' ergized upon .the'engagement ofslow. speeds leveling contacts 32. This relay, uponopen-, ation; causes the engagement of,`- contactsll)` y 120.A completingthe circuit for coill This. circuit'niay be traced' from the:leftf.' hand blade of switch 42,.by wayof-lin'e-:79f through cont-acts A v50,byiwayo1".'"li'nerl22 through contacts D 120, up series Aiielclirelayc actuating fcil M' :123,- up Ehardbrakesswitch;l 95 actuating coilO; 124 andra portion'fl125 of reel' actance'f1'26, by :way: of; lin'ef127;th`r`ughf coil; L 121, 'line1'l28',ffby:wayof linef`=89 i contacts A.7 51,.-eto :the :right-hand.- blade foil switch 42. The circuit coniprisingcontacts.; L el3gfvdown-seies' ieldrelayy 'actatingil M 131,; downw hardtbrake: iswtch' actuatingi ampere turns' 1 in; vcoils M11-123 i and '324i afndn 1 I'0` reactanc-e'vportion 125 respectivelysathat the-v resultant.magnetizing'force for thermagneticl circuits: of the-'f relay, switch fand=fectncef .v v :iszero Thus neithenrelay Mnorswitchr' ItAwillf-be assumedizthatthe up levelingswitch.- operating roller 1. 112: .moves-bnto 'theengagement of' contacts 1L' '134,1'L`135g- B 136,1t L-137 andjL 138;' The separation'of contacts L 76 disconnects fieldwinding portions-175ml and 18, tield'winding'portion 17'beig con-i? which opposes the magnetizing orcegduei toi-43W more detail.'-A

L' the-circuit-tor coil- Gr 75."

.' -.Theseparation field Windingportion-l'. The effect of eld Winding portion 18 is reduced by resistance 140. z'lhefengagementof contacts L 138 completes a'short'circuit through fast speed leveling switch'contacts 34 for an adjustable portion; of'resistance 26. These connections causethe elevator motor to run at a desired leveling.- speed as 'Will-be explained later in Resistances 23 `andv 24 act to smooth out the changes in generator E. M. F. due to-these operations'. The purpose of the engagement 'of contacts L 136 and-L 137 will be 'explained later. It is to be noted that thel separation of contacts L 7 6 also breaks Thus had the current in coil Gv 75' not dropped to a suiiciently low value tol permitv relay Gr todrop out, as might result from the late centering of the carswitch, the disengagement of contacts L 76'in response to the engagement of up slow speed'- leveling contacts 32 insures the separation otcontacts G 97\.and theconsequent deenergization of holding coils B 71 and H1723 i:.f:3f.;f\.= y

ofl'contacts L 130 breaks the-parallel-circuitaround coils M 123 and O; 124 ancl 'reaetance' portion 126. Upon the separationof'contacts L 130, the reactance reduces'thecuirent' supplied to coils M 123 and O1"124z1t' valve belowe'thatrequired to' op# eratel relayM-:and switch O and thereafter pret'ents the rapidhuilding up of the current. thusjslightly delayingthe 'operation of the relayiandswitch; Switch O -maybe adjusted so that itrloperates f Valmost immediately the currentaagairi'starts Eto build Sup.' Switch O, uponxupe'ratipngtcauses thesep'aration of contacts'OiMl totbreakthecircuit for resistance 30;'iepxirallelfwith'fthe brkerelease coil 27 i Relay.- M'luporr operation, causes Tthe engagement ofconta'cts'M 142 tocomplete the circuit-fior the series-field switch actuating eoil N143. This circuit'ma'y'be traced from the left-hand blade of switch 42, by way'o'f 9throughrcbntacts-Aoybyway of line 128tl1rfouglncoil-N"143l andfcontact's.-M= 142, by way-0f line=89 through contacts- 51, tothe right-hand hlade fofswitch 42; Switch-N, up'onoperation, causes the separation of con- ,tacts N141, breaking-the circuit including resistance 29in shunt to thegeneratorseries ield'winding 16. The generator series eld coils are so :Wound ftha-t, Without the parallel resistance 29,tliey'would haye too great an effeet tor proper operation bf the car. The de# sired compoundingis obtained by employing the lev resistance shunt." Upon separation of contents N 144,`thestrength of the series field is' increased for the leveling operation so as to aid in obtaining the desired stopping operatinn. The short -delay in the action of re# la" and therefore the switch N, upon the initiation-ot the leveling opera-tion, is desirmle in order that the current in the generator armature-elevatormotor'arrnature circuit BEST AVAILABLE COP 5 may adjust itself to such-a Value that proper series field strength during the leveling-0peration may be obtained. As the carnears the third floor landing, roller 112 ridesoll' the vertical surface onto the oblique surface of cani 114. This results in the separation of up vfast speed leveling contacts 34, removing Y the short-circuit around resistance 118. The generator E. M. 1"., therefore, is again lowered and the elevaf tor motor runs at its siowest speed. i

Shortly before the car reachesl anexact level with the landing, the-roller 1'12rides off the obiique surface of cam 114, therebysepa'- rating the'sloui speed leveling contacts 32. 'lhe circuit for coils H 58,'B 5T and D 117' is thus breken. Switch B dfrop'sout causing the separation of contacts B 68, B 67andB`66 and the reengageinent-of contacts B' 65. The re engagement o t'contacts B 65`a-nd the-separation of contacts B 68 are in' preparatiopfor the next starting operation- Contacts B'66 and B 67 will lie-.referredt'olaterfiUp'i-slui speed eifeling relay D drops out-,casingtle separation of contacts 120 Tlisf'the cir cuit is broken forfcoils M 123, TO" 124 'and'L 121'. lelay-M.-and switch-L'drop out lnmediately but switch'O isdelayed'infit's action by the eiefct otreactance 126 anddisharge resistanc`e145. l Itis tolbe notedthat the discharge current for coil O 41-24fand '-thfe ,rea'etance passes throughdoi'vnfcoil O' 13 2 ii'such direction as ftd cause' Icoil O' '1 321tq'lassirstcoil O 124' inV 'maintaining switch" O in? operated condition Relay h f-,fipon'*droppingv lout', causes the separation ific'entacts M142,de energizing Y ser-ies? ield 'switclfactuatingi-cil N 143.- Swit'chwN- f dr'o'psff entita reconnect resistance 29' across' f the'gn'erator -se'riesieldz Switch L, upon dropping out; causes the 'separationgof 'cont-acts L 134, L 13533513E 136,513 13mm ALI 13e-and thcgeiigag'emene-bffco'- ta'cts'LTtan'd ;L"130 f Tl ie separation o'f'cn tcts- 11136,@ 137 -azndlLrSlnd the-engage; rn'ent 'of Ico''nttiets"13j-130 are preparation for the nentstartingloperatiohi Gntacts-L'ilSdr, L 135 and"-L '76"'will befrefei'I-edto'flaterl Switch Hl dropsro'utalong" 'witli'fswiteh B'nd relay D, causing theseparatioj ebntaets 81'l and H -8()'fandt he' engagement of'c'ontact's H' 'F8 andiH-Z .1 The:se'p'ziifationof contacts H" 8 1 is in preparation.- for the *next starting ogeratimi'.v The separation-0f co'ntac'tsfHv 80 brea-lrsthe circuit {ofthe-'brake release eoi`127; eiecting thev applicationof thef'brake The engagement of contact's'H 7 8 'during this op eration has no particular func-tion. '5 "1f'f The engagement of contacts 7--along withthe' separation off'co'ntacts' B66 andfB 67 of the'up direction st vitch and the1 sepa'.- ration ofcont-acts' L' 134 fand L 135 ndlth'e engagement of contacts L 7 6 of the slow-down switch disconnects 'ieldf 'Winding portion! 417 from mains- 40'-41'and connects bothfield winding portions' 17 and 11s-tothe generat r4 lis armature. The polarity ofthe latter connection is such that the generator sends current 'through the Whole lield Winding in such direction asto oppose the flux which produces the generator E. M. F., thus tending to destroy the residual flux of the generator field. Thus, .the brake being applied and the generator separatelyexcited ield Winding being disconnectedfrom mains l0-41, the car is brought torest level with the third floor landing Since the engagement of contacts O 1111 isdelayed, a hard applica-tion of the brake is obtained, assuring.4 a positive stop at the ending... o

In the event of an overrun, the operation of the switches is modified. Assuming in the above example .that the car overruns the third 'loor'to the extent of causing the engagement ofdown slow speed leveling contacts 33, a circuit is'completed for coils H 58 and C 102 and actuating coil E 146 of the down slow speedleveling'relay. This circuit may be traced through-coil H 58 as previously traced, by Way'gof line 103 througheoil C 102, contacts'33,and` coil E V14 t y Way of line 89 .throng-girl contacts A 5 1, to the right-hand bladerof switch 42. The relay E, upon operation, .causes the engagement of 'contacts E l47, comple ti ng:a circuit -for down coils M 131 and 0 '132 and lcoil L 121. This circuit maybe traced from the left-hand blade of switch 42, by wayof -line 79 through con- .tacts A, 5 0, by Way of line 148 through contacts E 147, coilsM 131 and() 132 and reactance portion-133, byway ofline 127 through 'will-,121? te .therght-handblade 0f Switch asi rer-i911Sly;twaalf,.v Due .tothe fact that entets-Lelpare afenggament, l1P @Oils and e0-1,1241. :are: t0nneeteflv in parallel vvit-hdovm coils -MQ- 1131and z0.132. Thus, as prerioeslrxelaned; the Swth L Operates. immediately, eansinggthe separation'of contactsL .130 and-.L 76 and the 'engagement of contactslj 134, L-:135.,'L.1;3 6', L 13T and 'L 138. Since-,contacts H17 are-separated and contactsuGilOvand C 106 arein engagement due to-theenergization of coi-ISH 5 8and C 102 respectively, the separation of contacts L 7 6 andthe engagement ,of contacts L 134A and L 135.1;cause the connection ofA field Winding portion 17 to mainsfflOf-#l and the connectionoilieldwinding portionlS to the gener! atorfarmature.. Asywillbe seenv from later description, Ysuchfconnections of the field ,Winding portions cause; the generation of an E. M. F. which causes the elevator motor to be returned to the floor in the down direction and which E. M. F. is of a value very near to that generated with the car' approaching the loorin the up direction.` Variations in the generator E. M. F. for the'leveling operations cause variations in' the -operationof the elevator motor. vBy causing the generation of more uniform voltages for leveling, as by t-he above. arrangement, suchv variations in the leveling operation are substantially eliminated.

Relay M and switch O do not operate immediately upon thefengagement of contacts E 147 and the separation ot' contacts L 130. When approaching the floor-in the up direc-l tion, the current fiowing through reactance portion 125 caused a fiux to be built up in the react-ance in one direction. Upon the separation of contacts l) 120, the current inthe reactance and coil O 124 discharged into resistance 145 tending to maintain the flux built up and, as previously explained, switch O in operated condition. Upon the enga-gementof contacts E 147 and the separation of contacts L 130 on the overrun, thev current supplied to coils M 131 and O 132 must reverse the flux in the reacance, thus taking a longer time to build up to a value sufiicient to cause the operation oi' relay M and switch O. Thus contacts N 114, depending for their separation upon the operation of relay M, remain closed temporarily to insure that the current inthe generator armature-motor armature circuit has fallen to a low value. Since the current in the series field Winding may be fiowing in a direction such as to cause the generation of an E. M. F. which is of properpolarity for operating the car inthe down direction, immediate increase in the strength of the Vseries field might result in an overrun in the down direction. As thecar returns to the floor. it is stopped by the separation of slow speed leveling contacts 33 in a-manner .similar to that described Jfor approaching the loor. .If the overrun is great enoughto cause the engagement Vof the down fast speedleveling contacts 35 asrwell as the-down slow speed leveling contacts 33,' resistance 118 is short# circuited, increasing the generator voltage and causing the elevator motor to run at its fast leveling speed. Further than this, the operation on an overrun is as above described. f l

. It is to :be understood that the' operator may, control both the acceleration and retardaton of the car by moving the car switch in' steps; Should the operator suddenly move the car switch from one position into the other, for'example from up into down position, injury to the system is prevented. by contacts B 65 which remain separated until the up direction switch drops out.

In variable voltage control systems'of the type wherein the elevator motorie supplied with current Jfrom the generator of a motor generator set, the generator is required to operate over a Wide range of E. Mi. F. values, varying from a maximum in one direction to a maximum in the other. When operating at low values of E. M. F., the armature volta-ge obtained for a given field current may vary over'a Wide range due to the varying effects of residual flux. This effect is very marked under leveling operating conditions Where l loo operation of the-system very markedlys-.L-:ln

order that the effects' of residual-flun'inaybe clearly seen, reference may be had'lt the its# suine hysteresis curve show-nf-in 'g This gure illust-rates the-cond1- Y small current is supplied to th' separately excited" field Winding of a separately. .terr generator, as -during leveling operation. -1'" :.t' Willhe seen that, :t'or a certain current value,

represented bv the maguetizing torce Mm.,

the E.; MQFO the g nerator may be any value hetween Vland V3 depending on the previous ,magnetic state of the machine and whether the car-is approaching the floor trom one-direct-ion-.or is returning to the tioor in this. direction afterl an overrun from the opposite-direction. V3 represents the miniinum value ot the. generator M. F. for a magnetizingtorce Mr/ n of equal but opposite value to magnetizing force Mm. Ghviously, fs uch-large- E. M. F.. variations mif'ht res u1 t in undesirable variations in operation under leveling conditions; These variations cannotwhe satisfactorily corrected by adjusting the amountof resistance in series 'ith the se, vz i i.-.at'ely excited field Winding. For exanipegtheamount ofresistance were decreased to the-value of V3, the value-of V 1f `{illso :would 'he-raised. Aresulting insa-n 'increasing -to run past the ount of resistance :6E-fett?? i i "ihfevyll'l' 0f vs-ialsmwould be lowered,

the ,possib ility-of gheing of too low a value: tcl-,return thacar tothe foor after an erstma-1515.131115., ities. @lues-0f V1 nndVg' Ceabemadeeearla en ital".leveling Opereties eelistivnsihe 'sysfieia'may be adjusted sdoastoJoht-ain more uniforf operation.- This Hel Winding portion 18 to the generator arreter and. saergizineieild,Winding P01'- @1911 i.For, convenience oiexplaining the action 0f, ,t l 1fe.portions17 and 18 of? the .field winding, a ssi11ne thatthe generator has been in op- F. eration..i ivith 'the portions connected across thei'nains zin.such-: -Inannenas to assist each otherandthat.'.as afinal'jstep in reducing thegenerator M. 1F.,both portions are disconnectedlffrom the mains and that portion18 is connected to the generator armature and portion. 1 7 left unenergized, the polarity' o'f;.tli e coniiection between the generatoraiymatureand. portion 18 being such that thegenerator sends current therethrough in a, directionto, oppose the flux which profe? ratei-fr 'ofthe machine. These values would be due ed result mayghe'attained oy connecting BEST AVAILABLE COF" 7 duces the generator E. M. F. The final values oii the generator E. M. F. under such conditions. are illust-rated in Figure 4. In this figure, the line X-#Y is the resistance line ofl the field andshovcs the relation between the voltage applied to the field Winding and thenumber lof ampere turns produced there- *by `Witli the hysteresis curve, as before,

in' lie'rst. andiA third angles, the line X-Y Winding portion 18, in accordance with of connect-ion assumed, is in the ourth angles. If both Winding lbeen lelt't disconnected, the gen- MF. would have assumed a value depending on the previous polarity nel?. 'eiiatoi l!! tofthe'residu'al fiux ot' the generator field. For convenience ot further explanation, assuine that. the previous polarity of the gcnerator corresponded with the polarity indi.- cated by M. F. value V8 at the time that Winding portion 1T ,was disconnected and winding portion 18 Was connected to the armature. l t is to be understood that the value ot' the generator' E. M.'F. at the instant of the change of connections would be determined by the time constant of the `field and therefore might hel greater than V Assuin ing, however, that the generator ,E..M. F. was at a value4 V8 at the instant of change, this" E. M. F. applied to winding portion 18 would tend to cause this portionV to.' exert a. magnetizing torce or" a value. M52." Such magnetizing force, howevenlopposing the fiuxwhich produced theiarmature E'. M. 1F., would cause a decrease -in` the valii'euof'the E. M. F., generated. A d'ecreased'iE.' M.v Fi Would simply meana decrease again in litho value of theopposing magnetizingjorcei As a.. resuit, a; state of .equilibriunfwould'be reached Where aiyftendency toma.: decrease in armature E. F. would= resi'iltin a decrease in opposing magnetizingv force with the -consequent increase in armature ELM. IF., i. e., oncethear1nature'- EL .Ma- Fris reduced to'a. Value Vi, a decreasolin'val'ue would mean that the opposing magnetizing force would tend to assume a value M63, forexample which would tend to increase-'tire .alue othe armature E. M.F. The valuefV'5 represents the armature E. M. F.-with the state of equilibrium obtained after a previousl a'rmature E. M. F. of the other polarity.

According to the preferred-arrangement, however, as previously explained, field wind'- ing portion 17 is energized from the mains when portion 18 is connected to the generator armature. vWith the Winding portions connected in this manner, conditions-become as illustrated in Figure 5. In this iigure, Mml represents the magnetizing force created by winding port-ion 17' with the car moving in one direction while MZ) represents the magnctizing force created hy Winding portion 18 for the state of equilibriumwith the car appreaching thefloor in this direction and MZ),L represents themagnetizing force created by winding portion 18 for the-state of equilibrium when'the car is being returned to the door in-this direction after an overrun from the opposite' direction. Graphically, the efect of the magnetizing force Mm'1 of Winding-portion-l7 is to shift the resistance line X-Y for Winding portion 18 -to the right. When the car is approaching the floor in this direction, thereiore,-the vfinal value of the armature E. M.F. is that'due to the differ-A ence in the magnetizing forces of the winding.portions,^i. e.,vMfm.1-Mb, and is rep# resented as V6. When the car is returning tothe door inthis direction after an overrun from the other direction, the final value of thearmature E. M. F. is that due to the differencein the magnetizing forces of the Windingfportions, i. e., Mull-M61, and is represented asV7. The armature E. M. F., therefore,- lies between the values V6 and V7, which vga-lues, relatively speaking, are very nearly equal.- ,'Thus the possibleirange of variationis much .smaller-l than when. an undivided-separately excited field winding is used explained in. connection with fFigure 3'.; .The increase in ieldcurrent. toobtain the desired iagnetizing; force Mm1` of the wind'- ingcport'on?17b'forf5tlre1voltages V6 .and'V7 is. effected .bytliefengagement-of contacts L 138 in'the systemdescribed. :Any tendency fonan-inciasein'thearmature E. under theabove described: conditions would. re-

' slti ii increasezin .the magnetiz'ing'iorce of th'eportion- 18,'and thus a decrease, ini the xit 'magnetizin'gforce, andiyice versa.

.fFItiis preferredtozutilizethe field winding pqrtionitf it'assjstgthe fieldx winding-17 'during carswitcliiopratioif Aasf-,described aboves The-arrangement 'ofth'e' 4fieldwindingimay. asiindicatedilr Figure 2:? Hierethe'field coils for-vtlienoi-thi aregrouped -together :to vbeudas;Turin' portion-17 while the' field coils' for the south .poles are' grouped-together to lisedi'asfwiiidmg"portion-#18S With the' switch thej'position illustrated, 'these' windingsare con'n'ected so 'as tolassist each' other;- providing alternate northand south polesa fThedirectipn-Qf the current isindi# catedrby arrows. The circuit foi-thefield windingmayfbe' tracedibyII-way o lineAV 74 through windingportion 17 constituting the poles, through coilfGe75, 4contacts L 76 and winding portion =18 constitutingthe S poles, to'line 89- Itis"tolbeunderstood that the manner of'windingis such as-to obtain the desired'-no1a.ritj,f.-f WVith the windingof switch L energized bjr-"the leveling switchcontacts, the switch'is moved intolits other position so as to'disconneetwinding portion 18 from the mains and to connect fitto the generator arma-Y ture with the proper polarity; The circuit for windingportion' 17 may'now be traced by way ot line-44 through winding portion 17, by way BESTAVAILABLE COP of line 170 though contacts L134, to line 89. v The circuit for Winding portion 18 may be traced fromthe lower armature terminal, line 171, a portion of line 89, by way of line 74 through winding portion 18, by Way of 11ne 70 for the Series field is such that the field due to 30 the series winding assists that due to the separately excited field winding portions, when the motor is lifting 'aload; Thus, upon the operation of switch L to cause the engagement ol its contacts L 134 and L 135 and the 85 separation of its contacts L- 7 6,' the current supplied to the field winding portion 18 is reversed. This istrue regardless of whether the elevator inotor is 'lifting or lowering a loadsince the polarity-.of the generator 'arm'a- 90 ture docs not change upon regeneration. The engagement of contacts'L 138 results 'inV an increase in niagnetining force due to the Yfield winding portion-"17 as-`previously`-eiiplaned.`

field 4winding 'portion 18"'wh'en the-'latter' is connected to the generatorf'armature serves to reduce the amount' o f current supplied to' this portion and therefoiezthe' niagnetizfingfforc produced' thereby, the 'resistance determining 100 leringievuipg'fyctsalu @alerter-faiths 105 residual flux of``thef1gnerator 'rifsubstantia'ily eliminated-'5; f Itfs'to'be" understood 'that the above. 'd'e'seribedz arrangement is; applicable to generators ootlier pole nlixnbers,ija lfo'iir the desired res'ulti,

fa-he seriesaelawindigiecis to the' 115 separately excited field, Winding portionstd obtain' the tle'sli-red"conditionsfduring opera.- tion. Undernorml gcar switch operation', when' these'vvf-indiiig'portons assisteahotlier,

the series feldwinding'acts intheiusixal man1 120 ner to "compensate 'forwaryingload' conditions'.l` During leveling conditions, when the elevator motor is'lifti'nga load', ,theeli'ect of the series field winding is to aid in bringing the' car to the fioorsincelthe current flow in 125 the series field Winding isi-in such directionfas to produce'a magnctizing force which assists that due to field winding portion 17 and 0p-- poses that due to field winding portion 18.'

Conversely, when the elevator motor is lower- The direction of the 75 Referring again to Figure 1, 'in order to guard against an openfcircuit in eld Windlng portion 18`during levelil'ig.v ,with the resultant increase. in generator EL M. F. and

therefore car speed when contacts L 138 are in engagement, the protective relay J may be employed." Along With the employment of relay J contacts L lland 137:ae employed to connect resistance 150 ,to the generator armature.l The protective relay actuating coil J'. 151 is connectedbetyveen la point en this resistance 'and theV mid pointof Ifield Winding portion 18. bridgecircuit is thus `formed and is; sof balanced thatunder normal leveling.psratingfonditionsnacrrentqws thlg'h .QilJ- lll.' Howeverlitlan'piie erj- .cuitlbccuifsinf field Winding pOliQn 1 8 itself er' in; thefirct:fforjfresstanel.1503.11rent .flojvs throughc'o'il J '151, causing the opera- .fioa Qfihe. relays .The re1ay, upon soperatime; .Causes the eePrefQI '01. ,contacts- J. `i? Ain the ciicfuit 'for 'thaacliatne'faol A. f if the .Peetlfswith- Belen-'1.55 'Ireiby -fl'thelatehed tipeta'mailtaifevtects. J 4-7 .siam-atea .oneaerayiisaared; unt-i1 .marialli ,reset- Switch.- .Aalllli drpp'll'g ,enti-aims .the separation @f ,oiitaets fAf: .f5.0 and A'51. Thus tlediian S fliseeetedirpn lainallauil 141." end-the -brake e efachfside of .thezhndge .circa t tlegehdfie anneau alacant f anni drannsfwm andgdolnot 'causethe'operati' 'ofthe p ifote- `the scope'tilgeref, it s intended that allmat- .tive .relay Ji: Howe-Yer',- ff.-,.rje`sice 1.4.0 iin --Qn .side i the. bridge dreuxsrlanie; .1t ,iialv he. desirable to.- divlide. itjnto. halves, putting one-half in onefs'ide thelridfiircuitfand the other. .haii the other; side. Sucharrangement :yvon-ld. result in1 a ,perfectbalan ce and would insure that relay"J vvouldnotlhc ,operated ,under vtransient .voltage `tonditions. 1- -ldSreL ,the auxiliary-Iprotetiellrelay K, preferably' om@ .same types-relay .J Sio .as .to maintain 5 .its contact-s K 48 Separated untlgmanually reset n 'c e' the relayhas oper- `ated. may he .employed to .protect against an accidental. open circuit forthe coil '1J 15,1 and againsttheaccidental short circuit of resistance. 26 ..\during leveling, .operation which wouldresult inI an excessive voltagebeing I applied totield. windingiportion 17. Itis to be noted that thefauiliary protective -re- 5154. Undernormalarswitch operatingY conditions coil'K 153 isconnected in series with coil J 151:across onehalf of field wind- ;mg. .Partien ..1.8- and, .0.1..;K 154 aCrQSS field initialisiert Y BEST AVAILABLE COS` winding portion 17. By means ot' the resistances 14.55 and 156,` the current supplied to the cilsinay'headjiistled so that the ampere turns of' one coil neutralize those of the other. If the circuit-for coil'J 151 should be accidentally` op'ne'd; coil K 154 alone would be energized, causing the operation of the relay K. Relay K, upon operation, causes the separation of contacts K 48 in the circuit for the potential switch actuating coil A 45. Thus the caris brought to a'stop in the manner atreve` desci'ihed.'4 During the leveling operation,"co`il K' 1 53'is short-circuited by contacts `L v137 so thatonly coil 'K 154 is energized. Coil K 154'is designed, however, so as to cause the operation of the auxiliary protective relay 'K to effect thejstoppingfo the car when an excessive voltage, such as would result from thefSliQrtv-circ'uiting ofhresistance 26, is lapplied to tl1'e 'coil. 'll he coils of relay K are wound with'- a larger number of turns than '1r:Inponibnatiom'anelevator car, a motor :thereoagenerator 'Qrsfupplying current to said lnotprtsaidxgener'ator'having a field v as'oii'ifce' fcurreiit Qiftlie v l .meansffar aungs'ajdjmotor to. bring the Lc'ar tua levlwitlia desired landing regard- 'less -vvllthe' thecar overruns or underruns Vsaid landing, said last included means comprising means for dis :o"nne'ct ingv a portion of` said field ,Winding from said source and connecting it to thearmatureof said generator.

2. In combination, an elevator car, a motor therefor, a generator for supplying current to said motor, said generator having-a ieldfwinding, means for driving said generator, a sourceof lcurrent for the field winding, and means for causing said motor to bring the car to a level with a desired landing regard- 4'0 'means for less of whether the car overruns ornnderruns saidlanding, said last included means concsaid landing, said second named means com-v prising means forldis'connectingja portion of said eld winding from saidsou'rce and connectingit tothe armature ojsaicl generator zo and means for reducing the Voltage applied to said portion of the eld winding below that o the generator armatu re. 4, In combination, an elevator'car, a motor therefor, a generator'for supplying current .to 25 sa 1 id n i otor, saidgenerator having a .field winding, means 'for driving'said generator, a source'. of curre'nt Efor, the iield' winding, a insistence. and Ieeilsfrasihg' 's smp'tor fo bring .the dt-'t6 e lfvlf with afdsied lr'- 30 ingregai'dlessof whether the' car overrunsior edeirui :Seid den dine. Seid 'last-1'1sl11'ded .hiee Cmprilsmes irdisenetinse porti1'1`. o"f sa'id' eld" winding rfro'nr said BEST AVAlLABLE COP` therefor, generator for supplying current 'to said motor, 'said generator having a iie'ld winding comprising a plurality or' coils, one on e'ach field pole, means for driving said generator, a Source of current, means for connecting the coils to saidsource Ain such manner as to excite the alternate poles for opposite'po'l'arities, and means for causing the motor to bring the carto alevel with a desired landing regardless of whether the car overruns'or underruns said landing, -said second included'nieans 'comprising'-means for disconnecting the coils of alternate poles from said source and vconnecting them to the generator armature in such manner as to reverse their excitation.

In combination, an elevator car, a motor therefor, generator for supplying' currentto motor, said generator having a field comprising a pluralitylof' coils, one

onea'ch lield 'pole, mean s 'for driving said gencrater, asour'ceof current, means for connecting' c'oils tof'saidsourcein such Vmanner afs to excite the alternate poles for'opposit'e polaijit'ie's', 'means-'for 4can'sir'ig the motor to bring the car toflevelwith a desiredlanding regjdles'sbf AWhether the -car overruns or underruns' landing, 'said 'second included mans'. @misses man@ di'sicnnecmg the' Qnsggqfgalrgmate po'ls-jfmm'saiasr 'o5 and connecting them to the generator. armasch'iiiannerfas toreverse their excitaio ':afld aiisfor' thevOItag'e'a'pt loils'of alternate poles below that 'ion car ata certilinsped, and 'means for causing b5 In conibina'tviom'an elevator car, a ni'otor 'ii-'toman' leveling' switch, 'means responsivev 'to the operation'flsaid lieveling switch for cans- "ing a' change the' 'strength tor' 'th ej generator "12o diie tothe 7series field WindingA -for aV gi ven armature 'currentt and 'mea-ns -for delaying the operation of the firstnainedmeans for a 'longer periodof'tiine in response to the operlation of the levelingswitchto canse there '125 "turn'of the car after it 'overruns 'thelanding than in'response to the'operation'of thelevel'- 'lin switch to causethe car to "c'oi'ne to, the landing' :isit approaches thelanding.

"11. Infcombina'ition, an el'cv'zitorcar, amotor -13o therefor, a generator for supplying current to the motor, said `generator having a series ield Winding, means for driving said gener-` ator, a leveling switch, means responsive to the operation of said leveling switch for causing a change of ampere rturns of the seriesVV field for a given armature current, and means- 'or delaying the operation of the irst named means for a longer period of timewhen the car overruns the landing,l than When it approaches the landing. Y

l2. In combination, an elevator car, a motor therefor, a generator for supplying current to said motor, said generator havinga series field Windng,'means for driving said generator, a resistance in parallel with said Winde-EeTAi-Axmere Coal ing, means for causing the motor to bring the car to a level with a desired landing, means responsive to the operation of the first namedmeans, for disconnecting said resistance from said field Winding, and means for delaying the operation of the'second included means for a certain interval of time upon the operation ot the first named means as the car approaches the landing and for delaying the operation of the second included means for a longer interval of time upon the operation of the iirst named Vmeans to caused the motor to return the car to the landing after an overrun.

kInV testimony whereof, I have signedhmy namel to this specication.

LEE I. DAVIS. 

